Abstract:
Chronic low backache is an important health problem amongst Sri Lankans. The present study was undertaken to [i) determine the causes and risk factors for low backache.[ii) to describe age related changes in the number of cartilage cells in lumbar discs, intima media thickness of lumbar arteries and atherosclerosis of abdominal aorta and lumbar artery openings. I. [iii) to determine the association between such changes in the lumbar arteries and in the abdominal aorta with the number of cartilage cells in lumbar discs. iv) to describe the gross anatomical features of lumbar arteries. Initially, a case control study was carried out among 459 cases (patients with low backache) and 502 controls. Data was collected using a pretested structured interviewer administered questionnaire. Poor posture (OR=128.2), lack of exercise (24.5), positive family history (OR=16.2), education to less than the sixth grade (OR=2.2), daily alcohol consumption (OR =3.4), BMI\>24.9 (OR=1.5) and monthly income of more than Rs.20,000 (OR=2.6) were found to be significant independent risk factors for low backache. Another case control study was done on 130 cases (patients with low backache) and 133 controls assessing postero-anterior and lateral radiographs of the lumbar-sacral spine. Disc space narrowing (OR=16.9) and an Antero Posterior ratio of lumbar vertebra less than 0.9 (OR =10.1) were found to be significantly associated with low backache. Vertebral osteophytes and spondylolisthesis were not significantly associated with low backache. A descriptive cross sectional study was done on 31 adult postmortem specimens. Histological sections of the fourth lumbar discs and fourth lumbar arteries were prepared. The number of cartilage cells in lumbar discs (r= -0.45) and Intima Media Thickness (IMT) of lumbar arteries (r=-0.74) had a significant negative association with age. When compared to individuals under 43 years (median age of sample), individuals over this age were 12.5 times more likely to have atherosclerotic changes in abdominal aorta and lumbar artery openings. IMT of lumbar arteries and atherosclerotic changes in lumbar arteries did not have a significant association with the number of cartilage cells in the intervertebral discs when age was taken into account. Dissections were done on 109 adult cadavers to describe gross anatomical features of lumbar arteries. First to the fourth pair of lumbar arteries arose from a common single stem in 12 percent of cadavers and passed anterior to the crura of the diaphragm in 17 percent. There were several variations in the gross anatomical features of lumbar arteries from what is described in the literature. According to results of the present study, risk factors for backache among Sri Lankans are similar to risk factors found in other countries. In this study vertebral osteophytes and spondylolisthesis were not significantly associated with low backache. The present study was able to identify a new cut off value for A/P ratio that had a significant association with low backache, and for the first time demonstrate an association between the number of cartilage cells in annulus fibrosus and age of the subject. Several gross anatomical variations of lumbar arteries found in this study have also not been documented previously.